package com.alex.wechat.mp.util;

import java.security.MessageDigest;
import java.util.Map;
import java.util.Random;
import java.util.SortedMap;

/**
 * createSHA1Sign创建签名SHA1 getSha1()Sha1签名
 * 
 * @author Debenson
 * @since 0.1
 */
public class Sha1Util {

  public static String getNonceStr() {
    Random random = new Random();
    return MD5Util.md5Encode(String.valueOf(random.nextInt(10000)), "UTF-8");
  }

  public static String getTimeStamp() {
    return String.valueOf(System.currentTimeMillis() / 1000);
  }

  // 创建签名SHA1
  public static String createSHA1Sign(SortedMap<String, String> signParams) throws Exception {
    StringBuffer sb = new StringBuffer();
    for (Map.Entry<String, String> entry : signParams.entrySet()) {
      String k = (String) entry.getKey();
      String v = (String) entry.getValue();
      sb.append(k + "=" + v + "&");
      // 要采用URLENCODER的原始值！
    }
    String params = sb.substring(0, sb.lastIndexOf("&"));
    return getSha1(params);
  }

  // Sha1签名
  public static String getSha1(String str) {
    if (str == null || str.length() == 0) {
      return null;
    }
    char hexDigits[] = {
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

    try {
      MessageDigest mdTemp = MessageDigest.getInstance("SHA1");
      mdTemp.update(str.getBytes("GBK"));

      byte[] md = mdTemp.digest();
      int j = md.length;
      char buf[] = new char[j * 2];
      int k = 0;
      for (int i = 0; i < j; i++) {
        byte byte0 = md[i];
        buf[k++] = hexDigits[byte0 >>> 4 & 0xf];
        buf[k++] = hexDigits[byte0 & 0xf];
      }
      return new String(buf);
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }
}
